When 'n' is divisible by 5 the remainder is 2. What is the remainder when n2 is divided by 5 ?

Answer: Option D

$$\begin{array}{rl}& \frac{\text{n}}{5}\Rightarrow \text{remainder}2\\ & \text{if we put n = 7}\end{array}$$
Then it satisfies above situation
$$\begin{array}{rl}& \text{so n = 7}\\ & \frac{{\text{n}}^2}{5}=\frac{7^2}{5}=\frac{49}{5}\\ & \Rightarrow \text{remainder = 4}\end{array}$$